Arc lamp of the sealed type



Jun? 1927 F BAHR ARC LAMP OF THE SEALED TYPE Filed Feb. 21. 1924 Invent or FPH i Bah!" 9y flwm/b QZ His Atfir ngy llatented June l- L TQZZT.

FRITZBAHR, or GHARLOTTENBUBG, GERMANY, lasers-non T0 eennnar. steers-arc COMPANY, A CORPORATION 01" NEW YORK.

Anc LAMP or THE SEALED TYPE.

Application filed February 21, 1924-, Serial No. sauce-and in Germany May a, 1923.

My invention relates to are lamps and more particularly to are lamps of the sealed type, a type of which is the tungsten arc lamp; Lamps ot'this. type havebeen suggested for use for projection purposes.

When so used, the lamp should be placed as close as possible to the lens if the necessity of a particularlylarge condensing lens is to be avoided. The tungsten arc lamps which have been heretofore provided were rather small, being in size smaller than the incandescent lamp. This small type had the objection that the bulb would become blackened very considerably after a comparatively short burning period.

One of the objects of my invention is to overcome this dii'liculty by providing a special screen internally located in the bulb, the electrodes being located behind or within the screen. This screen is provided with an opening opposite the electrodes between which the arc is formed. \Vith this arrangement, a draft is created toward the opening in the screen by the gas filling in the bulb which becomes heated when the lamp is running. This current flows through the opening toward the electrodes and upwardly through the screen which serves as a conducting chimney. The gas current, thus flowing couireraets or opposes the metal vapors or metal particles ejected from the neighborhood of the arc and prevents these vapors or particles from reaching the glass wall of the bulb through which the rays must pass out of the bulb. Therefore, the bulb is kept free from blackening in the regions'through which the rays must pass in order to reach a condensing lens, screen, or other equipment.

One of the objects of my invention is to provide a screen which may be given a chimney-like torm and which may surround the electrodes as a jacket. With such a provision, the evaporated electrode material can deposit, in the main, on the interior of this jacket. The flow of the gas through the opening in the jacket toward the interior can be very materially increased by having the lower ends of the jacket closed. Therefore, the jacket may engage the lower wall of the bulb and-be fused to the latter. The opening in the jacket is made so that the condensing lens is completely covered by a cone of light. The size of the slot angle formed by the light can be varied by changing the distance of the electrodes from the opening. If desired, these electrodes can be mounted eccentrically in the bulb and in the jacket. 7

It is also'an object to provide other de tails of improvement tending to increase the efiiciency and serviceability of a lamp of the above character.

To accomplish the foregoing and other useful ends, I provide means hereinafter more fully described and claimed in connection with the accompanyingdrawing wherein different practical designs'of the lamp, accordingto the invention, are shown.

Figs. 1 and 2 show a tungsten lamp with the screen mounted in front of the electrodes, Fig. 2 being taken as a side view oi Fig. 1.

Figs. 3 and l show two similar views of a design in which the electrodes are surrounded by chimney-like jacket.

Figs. 5 through 8 illustrate other terms of the lamp having chimney-like jackets.

The lamp shown in Figs. 1 and 2 comprises a small incandescent lamp-like bulb a, which is provided with a base Z), or the usual type. Through the stem 0, the lead-in wires (Z are brought into the lamp to the spherical electrodes 0. The electrodes are surrounded'by the screen f. This screen may be fastened in position in any suitable manner as for example by mcausof the wires g. At the level of the electrodes 0, the screen 7 is provided with an opening it which permits rays of light from the lamp to pass freely outward. 3y the screen f the gas filling which is heated when the lamp burns, is directed, as indicated by the arrows. As the arrows indicate, the gas is drawn in through the opening in the screen through which the rays pass out. This current prevents the expelled particles of metal from depositing on that portion of the bulb which comes within the cone of light.

The screen can be of any suitable shape. It can be made of a flat plate, for instance. However, as shown in Figs. 3 and 4., the screen is advantageously given the former a cylinder-like acket 7" which surrounds the electrodes and which is fastened or fused to the bulb a by means ofsmall feet 5 The draft of the current-is of course intensified by the chimney-like jacket and at the same time, the circuit of the current is caused to follow certain paths so that the metal particles are deposited mainly within the jacket so that even the bulb as a whole remains entirely free from deposit for some time after the lamp is put into operation. The oplning h in the screen is advantageously made of such dimensions that the condcnsing lens '5 of the projection device comes entirely within the cone of light on the lamp.

As shown in Fig. 5, the protective jacket f can be closed at its lower end by a plate is and fastened to the bulb the upper end by the supporting arms Z. By this arrangement, the flow oi gas filling through the lower opening of the jacket as shown in Fig. i, can be eliminated and the how or gas through the passage opening it can be intensified considerably. Furthermore, the protective jacket can be made as long as shown in 6, so that its lower rim may rest against the wall a olthe bulb. In this case, the jacket is closed directly by the bulb and of course need not be clos :d by a special plate such as the plate 7.: in Fig. 5.

The protective jacket can be also provided with a turned out. rim m, Fig. 7, which may be fused to the bulb so that the latter closes oil the jacket as in Fig. 6.

As shown in Fig. 8, the electrodes 6 can be arranged eccentrically with respect to the bulb a and the jacket in such a manner thatthe electrodes will be located closer to the opening With this ai.'r:.mgement, the solid angle of the lightcone is increased so that a larger condensing lens could be used. The contrast between the two arrangements can be appreciated by comparing Figs. 4 and 8. The screen or jacket can be fastened in the lamp in any suitable manner and this screen may be made of glass, but it may also be made of other material, such as mica, or even metal.

In view of the disclosure, it is obvious that my invention may be applied in other forms which will readily suggest themselves and therefore I do not wish to be limited to any particular construction other than that talling within the scope of the claims appended hereto.

l Vhat I claim as new and desire to secure by Letters Patent of the United States, is:

1. In an electric lamp, the following elements in combination, a source of light sealed within an envelope, said envelope having a gas enclosed therein, a tube, said source located within said tube, an opening in said tube, said elements so disposed as to create a draft of said gas through said opening for preventing the passage of emanations from the light source through said opening, said tube vertically disposed and having said opening at the side and having also an opening at the top with the lower end closely whereby the said draft after passingthrough said opening, passes out through said top opening.

2. In a tungsten are lamp with an are surrounded by a sealed envelope, said envelope having a gas therein, said are enclosed by a screen within the envelope for cutting otl'emanations' from the light source, a hole in the side of said screen through which a beam of light may pass, said elements so disposed as to create a draft through said opening to prevent emanations from passing through said opening and d rkening the envelope about the region through which said beam passes through the envelope.

A. tungsten arc lamp comprising electrodes in a sealed envelope containing a gas and comprising also a shield between the electrodes and the envelope for preventing emanations from the electrodes from darkening the envelope, and an opening in the shield for permitting rays of light from the arc to pass through, said opening so located with lGfGlillQG to the arc electrodes that circulation of the gas within the envelope takes place through the opening toward the electrodes to oppose the passage oi. emanations from the electrodes through the opening toward the envelope.

In a lamp, a sealed envelope, a pair of electrodes between which an arc is adapted to be established, said lamp having in combination a solid screen about the electrodes for preventing emanations from the electrodes from striking the envelope, an opening in said hield to permit rays of light from the arc to pass through, and a gas in said envelope serving as a shield to oppose the passage of emanations from the are through said opening and striking theenvelope, said opening being so disposed with respect to the electrodes to promote a circulation. of the gas through said opening toward said electrode.

5. An electric lamp comprising a light source within a sealed envelop, said envelop containing a gas, said lampcomprising also a shield within the envelop, said shield being located between the light source and the env lop :lor preventing emanations from the light source darkening the envelop, and an opening in the shield for permitting rays of light from the light source to pass, there through said opening being so located with reference to the light source that circulation of the gas takes place through the opening toward the light source to oppose the passage of emanations through the opening toward the envelop.

In witness whereof I have hereunto set my hand this 28th day of January, 1924-.

FRITZ BAHR. 

